[citation][nom]crom[/nom]They probably want to keep the internet cafe's clean. After all, most people access the net that way, not from home.[/citation]
Then China should force internet cafe's to install filters on their PC's and routers, if they haven't already. No, the simple answer is that China's morality police have deemed porn innapropriate and are doing everything they can to prevent its access. Many Muslim countries probably already do the same thing and we just don't hear about it cause they don't go after Google, they handle it all internally.